Electronic devices with the ability to store information (electronic devices) are an important part of society. Electronic devices influence almost every aspect of life, ranging from business transactions to interpersonal communications. Examples of these devices are cellular telephones, personal digital assistants, and personal computers. One important aspect of electronic devices is the ability to store the information in digital memory, which stores information as a series of I/Os. A typical electronic device may have several different types of memory. One memory type is ROM (Read-Only Memory). ROM is a non-volatile memory type that a system can write to only once. Non-volatile memory is memory that can retain information without a draw from a constant source of power. ROM systems can read the information stored in the memory, but ROM systems cannot re-write new information to the memory.
Another type of memory in an electronic device is RAM (Random Access Memory), which is memory that allows information to be read in any order regardless of its stored sequence. RAM is the main working area for an electronic device. An electronic device can read the information stored in the RAM and an electronic device can write new information to the RAM. However, an undesirable aspect with RAM is that most types of RAM are volatile memory types, meaning that they need to draw from a constant source of power to retain their memory.
A common form of RAM is Dynamic Random Access Memory (DRAM). In an integrated circuit, each bit of data is stored in an individual capacitor as an I/O. The capacitors lose voltage due to natural leakage and stored data is lost unless the system recharges the capacitor. The reason for the term Dynamic refers to a constant activity taking place (e.g., the constant recharging of the capacitor). There are several variations on DRAM, such a video DRAM.
Other memory types exist in attempts to address undesirable aspects of ROM and RAM. One of the basic memory types created to address such aspects is EEPROM (Electrically Erasable Programmable Read Only Memory) which is both non-volatile and capable of multiple writes and reads. However, EEPROM is relatively expensive to manufacture, thus making use impractical for many personal applications. Flash memory technology is an alternative to EEPROM. In addition to processing the advantages of EEPROM (namely that the memory is readable, re-writable, and non-volatile); flash memory is also relatively cheap to mass-produce. The economic factor makes flash memory much more desirable for personal applications, such as storing of digital photographs and storing digital music files. Moreover, Flash memory devices generally have an expected life span of about one million programming cycles.